Effects of ZrC on microstructure, mechanical properties and thermal shock resistance of TiC-ZrC-Co-Ni cermets

TiC-ZrC-Co-Ni cermets with different ZrC contents were prepared by vacuum sintering. Microstructure, mechanical properties and thermal shock resistance were investigated. The results show that bright spherical grains in the microstructure are observed and their relative amounts increase with increasing ZrC addition. X-ray diffraction and energy-dispersive spectrometry results indicate that bright spherical grains are (Zr, Ti)C solid solution with more Zr content. The relative density, hardness and transverse rupture strength decrease with the increase of ZrC content. The fracture toughness, however, increases a little and then decreases. Thermal shock resistance of the cermets with 10%ZrC is the best and then declines with more ZrC addition. The parameter Rst of the cermets is also calculated on the basis of the physical parameters of the constituents to interpret the thermal shock of the cermets.